Muslims threaten civilian safety again

An Islamic group has threatened the French after their operations in Mali and Somalia against Islamic militants in those countries.

France is assisting the government of Mali against the Muslims who are threatening and terrorising civilian life. France was also involved in a failed rescue attempt of a French citizen in Somalia, the man was being held hostage by more Islamic militants.

The UK government will now assist France and Mali in combating these extremists.

Muslims are also holding French hostages in in Niger, Nigeria and Mali.

The French government has stepped up security fearing more attacks on France.

Back in March last year Mohamed Merah killed 7 people in Toulouse, France, 3 soldiers and 4 Jewish people at a school.

Why is it that Muslims behave this way so often when other religious groups rarely (if ever) do?

Is it due to Islam being 600 years younger than Christianity and thus Muslims are behaving like Christians did 600 years ago?
Or is it because Islam only exists in culturally/socially primitive countries, (no Islamic countries in Western Europe, North America or Australasia) developing and under-developed countries?